A method for driving a transmission mechanism output power in response to an anticipated fluid-pressure gradient field is provided. The method includes sensing the change of direction of pressure gradient field at a desired location from the different area of the transmission mechanism within fluid. The method further includes constructing fluid-pressure gradient field based upon isolation-fluid apparatus or low-density fluid space installed on a transmission mechanism within fluid.

A method for driving a transmission mechanism output power in response to an anticipated fluid-pressure gradient field is provided. The method includes sensing the change of direction of pressure gradient field at a desired location from the different area of the transmission mechanism within fluid. The method further includes constructing fluid-pressure gradient field based upon isolation-fluid apparatus or low-density fluid space installed on a transmission mechanism within fluid.

A hydraulic transaxle comprises an axial piston hydraulic pump having a variable displacement, and a transaxle casing incorporating the hydraulic pump. The hydraulic pump includes a movable swash plate and a pair of trunnion shafts. The transaxle casing includes a pair of side walls, and includes a pair of casing holes each of which penetrates each of the side walls between an inside and an outside of the transaxle casing. The pair of trunnion shafts are passed through the respective casing holes. The swash plate is formed with a pair of swash plate holes in the respective side portions facing the respective side walls in the inside of the transaxle casing. Proximal end portions of the respective trunnion shafts are inserted into the respective swash plate holes. A distal end portion of one of the trunnion shafts projects from the corresponding casing hole to the outside of the transaxle casing.

A method for driving a transmission mechanism output power in response to an anticipated fluid-pressure gradient field is provided. The method includes sensing the change of direction of pressure gradient field at a desired location from the different area of the transmission mechanism within fluid. The method further includes constructing fluid-pressure gradient field based upon isolation-fluid apparatus or low-density fluid space installed on a transmission mechanism within fluid.

A method for driving a transmission mechanism output power in response to an anticipated fluid-pressure gradient field is provided. The method includes sensing the change of direction of pressure gradient field at a desired location from the different area of the transmission mechanism within fluid. The method further includes constructing fluid-pressure gradient field based upon isolation-fluid apparatus or low-density fluid space installed on a transmission mechanism within fluid.

A device for the deaeration of a hydraulic fluid of a hydraulic system has at least one hydraulic motor arrangement and a hydraulic fluid storage which is hydraulically coupled with this hydraulic motor arrangement. A suction device for sucking out the hydraulic fluid is associated with the at least one hydraulic motor arrangement such that the suction device guides hydraulic fluid out of the hydraulic motor arrangement into the hydraulic fluid storage by means of vacuum pressure (Δp). The suction device is constructed as a jet pump and is integrated in the return line between the hydraulic motor arrangement and hydraulic fluid storage.

A device for the deaeration of a hydraulic fluid of a hydraulic system has at least one hydraulic motor arrangement and a hydraulic fluid storage which is hydraulically coupled with this hydraulic motor arrangement. A suction device for sucking out the hydraulic fluid is associated with the at least one hydraulic motor arrangement such that the suction device guides hydraulic fluid out of the hydraulic motor arrangement into the hydraulic fluid storage by means of vacuum pressure (Δp). The suction device is constructed as a jet pump and is integrated in the return line between the hydraulic motor arrangement and hydraulic fluid storage.

An automatic transmission assembly for mounting to a power-source includes a torque converter operatively connected to the power-source. The transmission assembly also includes a turbine shaft for receiving power-source torque from the torque converter. The transmission assembly additionally includes a torque transfer system, having a gear-train and a hydraulic pressure operated torque-transmitting device, for receiving the torque from the turbine shaft and selecting an input-to-output speed-ratio of the transmission. The transmission assembly also includes an output member for receiving torque from torque transfer system and outputting the torque to drive a load. The turbine shaft defines a first passage configured to supply hydraulic pressure to the torque-transmitting device and a second passage configured to vent to atmosphere. The turbine shaft additionally defines a third passage fluidly connecting the first passage to the second passage and thereby configured to bleed air from the torque-transmitting device.

An automatic transmission assembly for mounting to a power-source includes a torque converter operatively connected to the power-source. The transmission assembly also includes a turbine shaft for receiving power-source torque from the torque converter. The transmission assembly additionally includes a torque transfer system, having a gear-train and a hydraulic pressure operated torque-transmitting device, for receiving the torque from the turbine shaft and selecting an input-to-output speed-ratio of the transmission. The transmission assembly also includes an output member for receiving torque from torque transfer system and outputting the torque to drive a load. The turbine shaft defines a first passage configured to supply hydraulic pressure to the torque-transmitting device and a second passage configured to vent to atmosphere. The turbine shaft additionally defines a third passage fluidly connecting the first passage to the second passage and thereby configured to bleed air from the torque-transmitting device.

A hydraulic drive unit includes: a pump; a pair of supply-discharge lines; a valve block; a sealed tank; a suction line that leads hydraulic oil in the sealed tank to the pump; a connecting line that connects an air vent port of the pump to the suction line; and a gas-liquid separator that separates air and the hydraulic oil flowing through the connecting line from each other. The pump is disposed upward of the valve block and the sealed tank in a vertical direction.